[Snowball-discuss] The =HH problem in Snowball discuss

[Martin Porter]

/* Usage: unescape <input >output

   Richard, can you make use of this as some sort of filter? I've been
   using it to view emails in the Snowball-discuss archive. Translates
   'equals' escapes between <PRE>...</PRE>.

*/

#include <stdio.h>

static int hex_value(int ch) {
    return ch <= '9' ? ch - '0' : ch - 'A' + 10;
}

static int eq(int * pointer_ch, char * s) {
    int l = strlen(s);
    int i;
    int ch = * pointer_ch;
    for (i = 0; i < l; i++) {
        if (ch != s[i]) {
            * pointer_ch = ch;
            return 0;
        }
        printf("%c", ch);
        ch = getchar();
    }
    ungetc(ch, stdin); return 1;
}

main() {
    int ch;
    while((ch = getchar()) != EOF) {
        if (eq(& ch, "<PRE>")) {
            while((ch = getchar()) != EOF) {
                if (eq(& ch, "</PRE>")) break;
                if (ch == '=') {
                    ch = getchar();
                    if (ch == '\n') continue; /* ignore line splits */
                    printf("%c", 16*hex_value(ch) + hex_value(getchar()));
                }
                else printf("%c", ch);
            }
        }
        else printf("%c", ch);
    }
    return 0;
}